We propose to study US trends in the prevalence of cognitive impairment and dementia by performing a new Aging, Demographics, and Memory Study (ADAMS 2010) that uses a similar methodology to that employed for the original NIA-funded study performed in 2001-2003. This new study will leverage the original ADAMS research team, the established national fieldwork infrastructure of the ADAMS and its parent Health and Retirement Study (HRS), and the lessons learned from the past 8 years of ADAMS work to create a unique publicly-available data resource that can be used by multi-disciplinary research teams to study the prevalence, causes, and consequences of cognitive impairment and dementia, and changes in them over the first decade of the 21st century. The specific aims of the project are to: 1) Conduct in-home clinical assessments of cognition in a sub-sample of 1000 HRS respondents age >70, and establish a consensus diagnosis of normal, cognitive impairment without dementia (CIND), or dementia;2) Provide to the research community a data set on the ADAMS 2010 sub-sample that contains information from the in- home assessments which can be linked to all prior and future waves of the HRS, including HRS biomarker data, HRS physical measures, Medicare administrative data, the HRS decedent interview, and the National Death Index;and 3) Use ADAMS 2010 data to derive a statistical model for assessing CIND and dementia for all HRS respondents age >70, utilizing the cross- walk between the "gold-standard" clinical diagnoses of CIND and dementia in the ADAMS and the core HRS survey measures of cognition and physical function. This model can then be used with future HRS waves to cost-effectively track population cognitive health in the US. The proposed ADAMS 2010, in conjunction with the original ADAMS and the on-going HRS, will provide the first nationally representative data to assess the prevalence and trends of CIND and dementia in the US. Given the wide-ranging impact of CIND and dementia on individuals, families, and society, and the projected large growth in the number of older adults with dementia in the coming decades, the proposed project to create an unprecedented set of nationally-representative data that can support multi-disciplinary research on key questions regarding dementia prevalence, risk factors and outcomes is truly a "Grand Opportunity." PUBLIC HEALTH RELEVANCE: Cognitive impairment and dementia are extremely common among older adults and result in disability that generates significant costs and burdens for families, the health care system, and public programs such as Medicare, Medicaid, and Social Security. The proposed research will collect data that will lead to a better understanding of trends in the prevalence, causes, and outcomes of dementia in the US and will, therefore, have major public health and public policy implications as we now enter the period of the most rapid growth of the elderly population in our history.